Summary: This research program focuses on the potential vascular consequences induced by biological products and pathogens with specific emphasis on endothelial activation and/or injury. Vascular endothelium, by virtue of its direct contact with the bloodstream, is a highly susceptible target for the adverse actions triggered by circulating products and/or pathogen components. Current investigations focus on the mechanisms of endothelial activation and/or injury mediated by (1) hemoglobin-based oxygen therapeutics, (2) lipopolysaccharide (LPS), and (3) anthrax toxin. Given that hemoglobin-based oxygen therapeutics may be administered to individuals predisposed or exposed to pathogens resulting from trauma, surgery, or possible terrorist attacks, studies also investigate the combined effects of hemoglobin-based oxygen therapeutics and pathogen components on endothelial cells.